Report lacking platform name in app header

crates/compiler/load/tests/test_reporting.rs

@@ -6009,6 +6009,33 @@ In roc, functions are always written as a lambda, like{}
         )
     }
 
+    #[test]
+    fn provides_to_missing_platform_in_app_header() {
+        report_header_problem_as(
+            indoc!(
+                r#"
+                app "broken"
+                    provides [main] to
+                "#
+            ),
+            indoc!(
+                r#"
+                ── WEIRD PROVIDES ──────────────────────────────────────── /code/proj/Main.roc ─
+
+                I am partway through parsing a header, but I got stuck here:
+
+                1│  app "broken"
+                2│      provides [main] to
+                                          ^
+
+                I am expecting platform name, like
+
+                    to pf
+                "#
+            ),
+        )
+    }
+
     #[test]
     fn platform_requires_rigids() {
         report_header_problem_as(

crates/reporting/src/error/parse.rs

@@ -3540,6 +3540,27 @@ fn to_provides_report<'a>(
             }
         }
 
+        EProvides::IndentListStart(pos) => {
+            let surroundings = Region::new(start, pos);
+            let region = LineColumnRegion::from_pos(lines.convert_pos(pos));
+
+            let doc = alloc.stack([
+                alloc.reflow(r"I am partway through parsing a header, but I got stuck here:"),
+                alloc.region_with_subregion(lines.convert_region(surroundings), region),
+                alloc.reflow("I am expecting platform name, like"),
+                alloc
+                    .parser_suggestion("to pf")
+                    .indent(4),
+            ]);
+
+            Report {
+                filename,
+                doc,
+                title: "WEIRD PROVIDES".to_string(),
+                severity: Severity::RuntimeError,
+            }
+        }
+
         _ => todo!("unhandled parse error {:?}", parse_problem),
     }
 }