error message for record update and missing module

compiler/can/src/env.rs

@@ -115,7 +115,11 @@ impl<'a> Env<'a> {
             }
             None => Err(RuntimeError::ModuleNotImported {
                 module_name,
-                ident: ident.into(),
+                imported_modules: self
+                    .module_ids
+                    .available_modules()
+                    .map(|string| string.as_ref().into())
+                    .collect(),
                 region,
             }),
         }

compiler/can/src/expr.rs

@@ -214,10 +214,17 @@ pub fn canonicalize_expr<'a>(
 
                 (answer, output)
             } else {
-                panic!(
-                    "TODO canonicalize invalid record update (non-Var in update position)\n{:?}",
-                    can_update.value
-                );
+                // only (optionally qualified) variables can be updated, not arbitrary expressions
+
+                let error = roc_problem::can::RuntimeError::InvalidRecordUpdate {
+                    region: can_update.region,
+                };
+
+                let answer = Expr::RuntimeError(error.clone());
+
+                env.problems.push(Problem::RuntimeError(error));
+
+                (answer, Output::default())
             }
         }
         ast::Expr::Record {