Bugfix. Check if Form is defined.
Bugfix. Check if Form is defined.

If we don't use the dataforms plugin then the Form object is undefined,
resulting in an error.

adozenlines/strophejs-plugins,bluecitymoon/strophejs-plugins,st-gwerner/strophejs-plugins,ebarbeito/strophejs-plugins,processone/strophejs-plugins,ebarbeito/strophejs-plugins,joachimlindborg/strophejs-plugins,processone/strophejs-plugins,bluecitymoon/strophejs-plugins,joachimlindborg/strophejs-plugins,adozenlines/strophejs-plugins,rerobins/strophejs-plugins,st-gwerner/strophejs-plugins,rerobins/strophejs-plugins