Convert AppWarning to TS

Signed-off-by: Šimon Brandner <simon.bra.ag@gmail.com>

src/components/views/elements/AppWarning.tsx

@@ -1,24 +1,20 @@
-import React from 'react'; // eslint-disable-line no-unused-vars
-import PropTypes from 'prop-types';
+import React from 'react';
 
-const AppWarning = (props) => {
+interface IProps {
+    errorMsg?: string;
+}
+
+const AppWarning: React.FC<IProps> = (props) => {
     return (
         <div className='mx_AppPermissionWarning'>
             <div className='mx_AppPermissionWarningImage'>
                 <img src={require("../../../../res/img/warning.svg")} alt='' />
             </div>
             <div className='mx_AppPermissionWarningText'>
-                <span className='mx_AppPermissionWarningTextLabel'>{ props.errorMsg }</span>
+                <span className='mx_AppPermissionWarningTextLabel'>{ props.errorMsg || "Error" }</span>
             </div>
         </div>
     );
 };
 
-AppWarning.propTypes = {
-    errorMsg: PropTypes.string,
-};
-AppWarning.defaultProps = {
-    errorMsg: 'Error',
-};
-
 export default AppWarning;