fix: do not show blank line diagnostic (#268)

src/parsing.rs

@@ -351,6 +351,8 @@ fn strip_bom_from_arc(s: Arc<str>, should_panic_in_debug: bool) -> Arc<str> {
 
 #[cfg(test)]
 mod test {
+  use pretty_assertions::assert_eq;
+
   use crate::diagnostics::Diagnostic;
   use crate::LineAndColumnDisplay;
 
@@ -465,6 +467,49 @@ mod test {
     );
   }
 
+  #[test]
+  fn test_err_trailing_blank_line() {
+    let diagnostic = parse_ts_module("setTimeout(() => {}),\n").err().unwrap();
+    assert_eq!(
+      diagnostic.to_string(),
+      // should contain some context by including the previous line
+      // instead of just a blank line
+      [
+        "Unexpected eof at file:///my_file.ts:2:1",
+        "",
+        "  setTimeout(() => {}),",
+        "  ~~~~~~~~~~~~~~~~~~~~~",
+        "",
+        "  ~"
+      ]
+      .join("\n")
+    );
+  }
+
+  #[test]
+  fn test_err_many_trailing_blank_lines() {
+    let diagnostic = parse_ts_module("setTimeout(() => {}),\n\n\n\n\n\n\n\n")
+      .err()
+      .unwrap();
+    assert_eq!(
+      diagnostic.to_string(),
+      // should contain some context by including the previous lines
+      // instead of just a blank line
+      [
+        "Unexpected eof at file:///my_file.ts:9:1",
+        "",
+        "  setTimeout(() => {}),",
+        "  ~~~~~~~~~~~~~~~~~~~~~",
+        "",
+        "  ~",
+        "  ...",
+        "",
+        "  ~"
+      ]
+      .join("\n")
+    );
+  }
+
   #[test]
   #[should_panic(
     expected = "Could not get syntax context because the source was not parsed with scope analysis."

src/types.rs

@@ -362,7 +362,7 @@ impl fmt::Display for ParseDiagnostic {
           .join("\n")
       })
       .unwrap_or_else(|err| {
-        format!("Bug. Please report this issue: {:?}", err)
+        format!("Bug in Deno. Please report this issue: {:?}", err)
       }),
     )
   }
@@ -413,14 +413,22 @@ fn get_range_text_highlight(
     source: &SourceTextInfo,
     byte_range: SourceRange,
   ) -> (&str, (usize, usize)) {
-    let first_line_start =
-      source.line_start(source.line_index(byte_range.start));
+    let mut first_line_index = source.line_index(byte_range.start);
+    let mut first_line_start = source.line_start(first_line_index);
     let last_line_end = source.line_end(source.line_index(byte_range.end));
+    let mut sub_text =
+      source.range_text(&SourceRange::new(first_line_start, last_line_end));
+
+    // while the text is empty, show the previous line
+    while sub_text.trim().is_empty() && first_line_index > 0 {
+      first_line_index -= 1;
+      first_line_start = source.line_start(first_line_index);
+      sub_text =
+        source.range_text(&SourceRange::new(first_line_start, last_line_end));
+    }
 
     let error_start = byte_range.start - first_line_start;
     let error_end = error_start + (byte_range.end - byte_range.start);
-    let sub_text =
-      source.range_text(&SourceRange::new(first_line_start, last_line_end));
     (sub_text, (error_start, error_end))
   }