Fix crash with --display=inline and trailing whitespace

Line numbers may be less than .max_line(), as .max_line() trims
whitespace. Ensure pad_after() is robust to this, and add a test.

I could only reproduce the crash in inline display mode, but in
principle this could be an issue in all modes.

Fixes #452

CHANGELOG.md

@@ -16,6 +16,8 @@ have few lines in common.
 Fixed an issue with unwanted underlines with textual diffing when
 DFT_BYTE_LIMIT is reached.
 
+Fixed a crash in inline display when the file ends with whitespace.
+
 ### Build
 
 Renamed the vendored parser directory to vendored_parsers/, as `cargo

src/display/context.rs

@@ -440,7 +440,7 @@ fn pad_after(ln: LineNumber, max_line: LineNumber, num_context_lines: usize) ->
     // Use one more line than num_context_lines so we merge
     // immediately adjacent hunks.
     for _ in 0..num_context_lines + 1 {
-        if current == max_line {
+        if current >= max_line {
             break;
         }
 
@@ -1034,4 +1034,11 @@ mod tests {
             ]
         );
     }
+
+    #[test]
+    fn test_pad_after_when_line_exceeds_max() {
+        let res = pad_after(2.into(), 1.into(), 5);
+        assert_eq!(res, vec![]);
+    }
+
 }