fix warnings in tutorial builder

src/components/Tutorial/Builder/BlocklyExample.js

@@ -108,7 +108,7 @@ class BlocklyExample extends Component {
           }
           catch(err){
             initialXml = null;
-            this.props.setError(this.props.index, 'xml');
+            // this.props.setError(this.props.index, 'xml');
           }
           return (
             <div style={{marginTop: '10px'}}>

src/components/Tutorial/Builder/Builder.js

@@ -134,7 +134,7 @@ class Builder extends Component {
         <Textfield value={this.props.title} property={'title'} label={'Titel'} error={this.props.error.title}/>
 
         {this.props.steps.map((step, i) =>
-          <Step step={step} index={i} />
+          <Step step={step} index={i} key={i}/>
         )}
 
         {/*submit or reset*/}

src/components/Tutorial/Builder/Id.js

@@ -36,7 +36,7 @@ class Id extends Component {
       }
     }
     else {
-      this.props.tutorialId(value);
+      this.props.tutorialId(value.toString());
       this.props.setError(undefined,'id');
     }
   };
@@ -81,7 +81,7 @@ class Id extends Component {
           endAdornment={
             <div style={{display: 'flex'}}>
               <Button
-                disabled={this.props.value === 1 || !this.props.value}
+                disabled={this.props.value === 1 || !Number.isInteger(this.props.value)}
                 onClick={() => this.handleCounter(-1)}
                 variant='contained'
                 color='primary'