Drop NUL terminator from diagnostic messages

src/diagnostics.zig

@@ -48,8 +48,10 @@ pub const Diagnostics = struct {
             if (diag) |d| {
                 var msg = e.getMessage();
                 defer msg.deinit();
+                // If the message ends with NUL byte, don't include it.
+                const size = if (msg.data[msg.size - 1] == 0) msg.size - 1 else msg.size;
                 d.data = .{ .err = e.getExitStatus() };
-                d.message = try d.allocator.alloc(u8, msg.size);
+                d.message = try d.allocator.alloc(u8, size);
                 @memcpy(@constCast(d.message.?), msg.data);
                 if (d.debug_print) std.debug.print("{s}\n", .{d.message.?});
             }
@@ -71,8 +73,10 @@ pub const Diagnostics = struct {
             if (diag) |d| {
                 var msg = t.getMessage();
                 defer msg.deinit();
+                // If the message ends with NUL byte, don't include it.
+                const size = if (msg.data[msg.size - 1] == 0) msg.size - 1 else msg.size;
                 d.data = .{ .trap = code };
-                d.message = try d.allocator.alloc(u8, msg.size);
+                d.message = try d.allocator.alloc(u8, size);
                 @memcpy(@constCast(d.message.?), msg.data);
                 if (d.debug_print) std.debug.print("{s}\n", .{d.message.?});
             }