Module: handle incremental update from ZIR with AST errors

1 files changed, 3 insertions, 1 deletions

diff --git a/src/Module.zig b/src/Module.zig
index 1520a7d1b2..c47e4fc234 100644
--- a/src/Module.zig
+++ b/src/Module.zig
@@ -3867,6 +3867,9 @@ fn updateZirRefs(mod: *Module, file: *File, old_zir: Zir) !void {
     const gpa = mod.gpa;
     const new_zir = file.zir;
 
+    // The root decl will be null if the previous ZIR had AST errors.
+    const root_decl = file.root_decl.unwrap() orelse return;
+
     // Maps from old ZIR to new ZIR, struct_decl, enum_decl, etc. Any instruction which
     // creates a namespace, gets mapped from old to new here.
     var inst_map: std.AutoHashMapUnmanaged(Zir.Inst.Index, Zir.Inst.Index) = .{};
@@ -3884,7 +3887,6 @@ fn updateZirRefs(mod: *Module, file: *File, old_zir: Zir) !void {
     var decl_stack: ArrayListUnmanaged(Decl.Index) = .{};
     defer decl_stack.deinit(gpa);
 
-    const root_decl = file.root_decl.unwrap().?;
     try decl_stack.append(gpa, root_decl);
 
     file.deleted_decls.clearRetainingCapacity();