Closes #1

* Added custom errors.
* Updated version number.

build.gradle

@@ -14,7 +14,7 @@ apply plugin: 'org.jetbrains.grammarkit'
 sourceSets.main.java.srcDirs 'src/main/gen'
 
 group 'org.swim'
-version '1.2.0'
+version '1.2.1'
 
 repositories {
     mavenCentral()
@@ -27,7 +27,7 @@ dependencies {
 
 // See https://github.com/JetBrains/gradle-intellij-plugin/
 intellij {
-    version = '2021.3'
+    version = '2021.3.1'
     plugins = ['PsiViewer:213-SNAPSHOT', 'com.intellij.java']
     updateSinceUntilBuild = false
 }

src/main/java/org/swim/annotations/ReconAnnotator.java

@@ -0,0 +1,22 @@
+package org.swim.annotations;
+
+import com.intellij.codeInspection.ProblemHighlightType;
+import com.intellij.lang.annotation.AnnotationHolder;
+import com.intellij.lang.annotation.Annotator;
+import com.intellij.lang.annotation.HighlightSeverity;
+import com.intellij.psi.PsiElement;
+import com.intellij.psi.PsiErrorElement;
+import org.jetbrains.annotations.NotNull;
+
+public class ReconAnnotator implements Annotator {
+    @Override
+    public void annotate(@NotNull PsiElement element, @NotNull AnnotationHolder holder) {
+
+        if (element instanceof PsiErrorElement) {
+            holder.newAnnotation(HighlightSeverity.ERROR, "Unexpected character")
+                    .range(element.getTextRange())
+                    .highlightType(ProblemHighlightType.GENERIC_ERROR)
+                    .create();
+        }
+    }
+}

src/main/java/org/swim/annotations/ReconHighlightErrorFilter.java

@@ -0,0 +1,12 @@
+package org.swim.annotations;
+
+import com.intellij.codeInsight.highlighting.HighlightErrorFilter;
+import com.intellij.psi.PsiErrorElement;
+import org.jetbrains.annotations.NotNull;
+
+public class ReconHighlightErrorFilter extends HighlightErrorFilter {
+    @Override
+    public boolean shouldHighlightErrorElement(@NotNull PsiErrorElement element) {
+        return false;
+    }
+}

src/main/resources/META-INF/plugin.xml

@@ -1,7 +1,7 @@
 <idea-plugin>
     <id>org.swim.recon</id>
     <name>Recon</name>
-    <vendor email="[email protected]" url="https://www.swim.ai/">Swim.AI</vendor>
+    <vendor email="[email protected]" url="https://www.swim.ai/">Swim</vendor>
 
     <description><![CDATA[Recon language support.
                     Recon is object notation with attributes, like if JSON and XML had a baby.]]>
@@ -26,6 +26,8 @@
         <codeStyleSettingsProvider implementation="org.swim.settings.ReconCodeStyleSettingsProvider"/>
         <langCodeStyleSettingsProvider
                 implementation="org.swim.settings.ReconLanguageCodeStyleSettingsProvider"/>
+        <annotator language="Recon" implementationClass="org.swim.annotations.ReconAnnotator"/>
+        <highlightErrorFilter implementation="org.swim.annotations.ReconHighlightErrorFilter"/>
     </extensions>
 
     <actions>