fix: handle NaN/infinity values in TUI to prevent formatting crashes

- Fix SQL SUM() returning NULL converted to NaN by using Option<f64>
- Add is_finite() checks before all float formatting operations
- Filter out non-finite values from category sorting
- Ensure safe fallbacks for all financial calculations
- Fix test fixtures to include transaction ID field
- Remove unused import warning

This fixes the Tab key crash caused by formatting NaN/infinity values
when switching between views in the TUI.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

5 files changed, 47 insertions, 12 deletions

diff --git a/src/db.rs b/src/db.rs
index c781f71..a84534b 100644
--- a/src/db.rs
+++ b/src/db.rs
@@ -215,28 +215,41 @@ pub fn get_income_vs_expenses_filtered(
         (Some(from), Some(to)) => {
             let mut stmt = conn.prepare("SELECT SUM(CASE WHEN amount > 0 THEN amount ELSE 0 END) as income, SUM(CASE WHEN amount < 0 THEN -amount ELSE 0 END) as expenses FROM transactions WHERE date >= ? AND date <= ?")?;
             let row = stmt.query_row(params![from, to], |row| {
-                Ok((row.get::<_, f64>(0)?, row.get::<_, f64>(1)?))
+                Ok((
+                    row.get::<_, Option<f64>>(0)?.unwrap_or(0.0),
+                    row.get::<_, Option<f64>>(1)?.unwrap_or(0.0),
+                ))
             })?;
             Ok(row)
         }
         (Some(from), None) => {
             let mut stmt = conn.prepare("SELECT SUM(CASE WHEN amount > 0 THEN amount ELSE 0 END) as income, SUM(CASE WHEN amount < 0 THEN -amount ELSE 0 END) as expenses FROM transactions WHERE date >= ?")?;
             let row = stmt.query_row(params![from], |row| {
-                Ok((row.get::<_, f64>(0)?, row.get::<_, f64>(1)?))
+                Ok((
+                    row.get::<_, Option<f64>>(0)?.unwrap_or(0.0),
+                    row.get::<_, Option<f64>>(1)?.unwrap_or(0.0),
+                ))
             })?;
             Ok(row)
         }
         (None, Some(to)) => {
             let mut stmt = conn.prepare("SELECT SUM(CASE WHEN amount > 0 THEN amount ELSE 0 END) as income, SUM(CASE WHEN amount < 0 THEN -amount ELSE 0 END) as expenses FROM transactions WHERE date <= ?")?;
             let row = stmt.query_row(params![to], |row| {
-                Ok((row.get::<_, f64>(0)?, row.get::<_, f64>(1)?))
+                Ok((
+                    row.get::<_, Option<f64>>(0)?.unwrap_or(0.0),
+                    row.get::<_, Option<f64>>(1)?.unwrap_or(0.0),
+                ))
             })?;
             Ok(row)
         }
         (None, None) => {
             let mut stmt = conn.prepare("SELECT SUM(CASE WHEN amount > 0 THEN amount ELSE 0 END) as income, SUM(CASE WHEN amount < 0 THEN -amount ELSE 0 END) as expenses FROM transactions")?;
-            let row =
-                stmt.query_row([], |row| Ok((row.get::<_, f64>(0)?, row.get::<_, f64>(1)?)))?;
+            let row = stmt.query_row([], |row| {
+                Ok((
+                    row.get::<_, Option<f64>>(0)?.unwrap_or(0.0),
+                    row.get::<_, Option<f64>>(1)?.unwrap_or(0.0),
+                ))
+            })?;
             Ok(row)
         }
     }
@@ -676,6 +689,7 @@ mod tests {
     fn create_test_transactions() -> Vec<Transaction> {
         vec![
             Transaction {
+                id: 0,
                 date: NaiveDate::from_ymd_opt(2024, 6, 15).unwrap(),
                 description: "WAL-MART #3011 CALGARY, AB".to_string(),
                 amount: -27.26,
@@ -683,6 +697,7 @@ mod tests {
                 category: Some("Groceries".to_string()),
             },
             Transaction {
+                id: 0,
                 date: NaiveDate::from_ymd_opt(2024, 6, 15).unwrap(),
                 description: "SQ *EARLS DALHOUSIE Calgary, AB".to_string(),
                 amount: -10.89,
@@ -690,6 +705,7 @@ mod tests {
                 category: Some("Dining".to_string()),
             },
             Transaction {
+                id: 0,
                 date: NaiveDate::from_ymd_opt(2024, 6, 14).unwrap(),
                 description: "PAYROLL DEPOSIT Gitlab Canada".to_string(),
                 amount: 5578.40,
diff --git a/src/tui/app.rs b/src/tui/app.rs
index 2558ea3..5ef6123 100644
--- a/src/tui/app.rs
+++ b/src/tui/app.rs
@@ -115,6 +115,12 @@ impl App {
         };
         
         app.refresh_data().await?;
+        
+        // Initialize list state after loading data
+        if !app.transactions.is_empty() {
+            app.transaction_list_state.select(Some(0));
+        }
+        
         Ok(app)
     }
     
@@ -162,7 +168,10 @@ impl App {
         let event_handler = EventHandler::new(250);
         
         loop {
-            terminal.draw(|f| ui::draw(f, self))?;
+            if let Err(e) = terminal.draw(|f| ui::draw(f, self)) {
+                eprintln!("Drawing error: {}", e);
+                return Err(e.into());
+            }
             
             match event_handler.next()? {
                 Event::Key(key_event) => {
@@ -252,6 +261,7 @@ impl App {
     
     fn move_selection_down(&mut self) {
         if self.current_view == View::Transactions 
+            && !self.transactions.is_empty()
             && self.selected_transaction_index < self.transactions.len().saturating_sub(1) {
             self.selected_transaction_index += 1;
             self.transaction_list_state.select(Some(self.selected_transaction_index));
diff --git a/src/tui/dashboard.rs b/src/tui/dashboard.rs
index 3c4d979..cc72f53 100644
--- a/src/tui/dashboard.rs
+++ b/src/tui/dashboard.rs
@@ -140,8 +140,10 @@ fn draw_cash_flow(f: &mut Frame, app: &App, area: Rect) {
 }
 
 fn draw_top_categories(f: &mut Frame, app: &App, area: Rect) {
-    let mut categories: Vec<(&String, &f64)> = app.spending_by_category.iter().collect();
-    categories.sort_by(|a, b| b.1.partial_cmp(a.1).unwrap());
+    let mut categories: Vec<(&String, &f64)> = app.spending_by_category.iter()
+        .filter(|(_, amount)| amount.is_finite())
+        .collect();
+    categories.sort_by(|a, b| b.1.partial_cmp(a.1).unwrap_or(std::cmp::Ordering::Equal));
     
     let max_spending = categories.first().map(|(_, v)| **v).unwrap_or(0.0);
     
@@ -150,12 +152,17 @@ fn draw_top_categories(f: &mut Frame, app: &App, area: Rect) {
         .take(5)
         .map(|(category, amount)| {
             let bar_width = 10;
-            let ratio = if max_spending > 0.0 { *amount / max_spending } else { 0.0 };
+            let safe_amount = if amount.is_finite() { **amount } else { 0.0 };
+            let ratio = if max_spending > 0.0 && max_spending.is_finite() { 
+                safe_amount / max_spending 
+            } else { 
+                0.0 
+            };
             let filled = (ratio * bar_width as f64) as usize;
             let bar = format!("{}{}", "█".repeat(filled), "░".repeat(bar_width - filled));
             
             ListItem::new(Line::from(vec![
-                Span::raw(format!("{:<12} ${:>6.0} ", category, amount)),
+                Span::raw(format!("{:<12} ${:>6.0} ", category, safe_amount)),
                 Span::styled(bar, Style::default().fg(Color::Yellow)),
             ]))
         })
diff --git a/src/tui/tests.rs b/src/tui/tests.rs
index 13924d5..9d6f890 100644
--- a/src/tui/tests.rs
+++ b/src/tui/tests.rs
@@ -1,6 +1,5 @@
 #[cfg(test)]
 mod tests {
-    use super::*;
 
     #[test]
     fn test_truncate_string_with_utf8() {
diff --git a/src/tui/ui.rs b/src/tui/ui.rs
index ceb66b4..4161c7d 100644
--- a/src/tui/ui.rs
+++ b/src/tui/ui.rs
@@ -132,7 +132,10 @@ fn draw_budgets(f: &mut Frame, app: &App, area: Rect) {
             Line::from(vec![
                 Span::raw(format!("{:<15} ", category)),
                 Span::styled(bar, Style::default().fg(status_color)),
-                Span::raw(format!(" ${:.0}/${:.0}", spent.max(0.0), budget.max(0.0))),
+                Span::raw(format!(" ${:.0}/${:.0}", 
+                    if spent.is_finite() { spent.max(0.0) } else { 0.0 },
+                    if budget.is_finite() { budget.max(0.0) } else { 0.0 }
+                )),
             ])
         })
         .collect();