fix expression indentation error

crates/reporting/src/error/parse.rs

@@ -529,6 +529,24 @@ fn to_expr_report<'a>(
 
         EExpr::Ability(err, pos) => to_ability_def_report(alloc, lines, filename, err, *pos),
 
+        EExpr::IndentEnd(pos) => {
+            let surroundings = Region::new(start, *pos);
+            let region = LineColumnRegion::from_pos(lines.convert_pos(*pos));
+            let doc = alloc.stack(vec![
+                alloc.reflow(r"I am partway through parsing an expression, but I got stuck here:"),
+                alloc.region_with_subregion(lines.convert_region(surroundings), region),
+                alloc.concat(vec![alloc.reflow(
+                    "Looks like the indentation ends prematurely after an expression",
+                )]),
+            ]);
+
+            Report {
+                filename,
+                doc,
+                title: "INDENT ENDS AFTER EXPRESSION".to_string(),
+                severity: Severity::RuntimeError,
+            }
+        }
         _ => todo!("unhandled parse error: {:?}", parse_problem),
     }
 }

crates/reporting/tests/test_reporting.rs

@@ -4586,6 +4586,28 @@ mod test_reporting {
     "###
     );
 
+    test_report!(
+        expression_indentation_end,
+        indoc!(
+            r#"
+            f <- Foo.foo
+            "#
+        ),
+        @r###"
+    ── INDENT ENDS AFTER EXPRESSION ────── tmp/expression_indentation_end/Test.roc ─
+
+    I am partway through parsing an expression, but I got stuck here:
+
+    1│  app "test" provides [main] to "./platform"
+    2│
+    3│  main =
+    4│      f <- Foo.foo
+                        ^
+
+    Looks like the indentation ends prematurely after an expression
+    "###
+    );
+
     test_report!(
         type_inline_alias,
         indoc!(