more errors for headers

compiler/reporting/src/error/parse.rs

@@ -2474,8 +2474,8 @@ fn to_header_report<'a>(
     alloc: &'a RocDocAllocator<'a>,
     filename: PathBuf,
     parse_problem: &roc_parse::parser::EHeader<'a>,
-    _start_row: Row,
-    _start_col: Col,
+    start_row: Row,
+    start_col: Col,
 ) -> Report<'a> {
     use roc_parse::parser::EHeader;
 
@@ -2495,6 +2495,33 @@ fn to_header_report<'a>(
         EHeader::Requires(requires, row, col) => {
             to_requires_report(alloc, filename, &requires, *row, *col)
         }
+
+        EHeader::IndentStart(row, col) => todo!(),
+
+        EHeader::ModuleName(row, col) => {
+            let surroundings = Region::from_rows_cols(start_row, start_col, *row, *col);
+            let region = Region::from_row_col(*row, *col);
+
+            let doc = alloc.stack(vec![
+                alloc.reflow(r"I am partway through parsing a header, but got stuck here:"),
+                alloc.region_with_subregion(surroundings, region),
+                alloc.concat(vec![
+                    alloc.reflow("I am expecting a module name next, like "),
+                    alloc.parser_suggestion("BigNum"),
+                    alloc.reflow(" or "),
+                    alloc.parser_suggestion("Main"),
+                    alloc.reflow(". Module names must start with an uppercase letter."),
+                ]),
+            ]);
+
+            Report {
+                filename,
+                doc,
+                title: "WEIRD MODULE NAME".to_string(),
+            }
+        }
+
+        EHeader::Space(error, row, col) => to_space_report(alloc, filename, &error, *row, *col),
     }
 }