fix(overmind): fix error to devtools when tracking effects error without actual error

Author: christianalfoni

packages/node_modules/overmind/src/index.ts

@@ -639,7 +639,7 @@ export class Overmind<ThisConfig extends IConfiguration>
               ...effect,
               args: safeValues(effect.args),
               isPending: false,
-              error: error.message,
+              error: error && error.message,
             })
             throw error
           })