Fix AssistContext panic on sole whitespace selection

Author: Veykril

crates/ide_assists/src/assist_context.rs

@@ -77,9 +77,14 @@ impl<'a> AssistContext<'a> {
             left.right_biased().and_then(|t| algo::skip_whitespace_token(t, Direction::Next));
         let right =
             right.left_biased().and_then(|t| algo::skip_whitespace_token(t, Direction::Prev));
-        let left = left.map(|t| t.text_range().start()).unwrap_or(start).clamp(start, end);
-        let right = right.map(|t| t.text_range().end()).unwrap_or(end).clamp(start, end);
-        let trimmed_range = TextRange::new(left, right);
+        let left = left.map(|t| t.text_range().start().clamp(start, end));
+        let right = right.map(|t| t.text_range().end().clamp(start, end));
+
+        let trimmed_range = match (left, right) {
+            (Some(left), Some(right)) if left <= right => TextRange::new(left, right),
+            // Selection solely consists of whitespace so just fall back to the original
+            _ => frange.range,
+        };
 
         AssistContext { config, sema, frange, source_file, trimmed_range }
     }