Bad error message when `@GeneratePrism` called with invalid `value=`

[mechite]

I have not tested this issue thoroughly.
For me, I was using an inner-class annotation, take this sloppy example:

// Example.java ============================================
package org.example;

@interface Example {
    @interface Whatever {
    }
}

// package-info.java  ========================================
@GeneratePrisms({
    // among other prisms...
    @GeneratePrism(name = "ExampleWhateverPrism", value = Example.Whatever.class)
})
package org.example;

If you now comment out the Whatever class, so it does not exist, and the reference in the package-info is invalid.
You are presented with a non-descriptive error. Take the following stacktrace, which I shortened, using mvnd package -e:

 Fatal error compiling
        at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute2(MojoExecutor.java:375)
        at org.apache.maven.lifecycle.internal................
        at org.mvndaemon.mvnd.builder..............
        at java.base/java.util.concurrent..............
        at java.base/java.lang.Thread.............
Caused by: org.apache.maven.plugin.MojoExecutionException: Fatal error compiling
        at org.apache.maven......................
        ... 12 common frames omitted
Caused by: org.codehaus.plexus.compiler.CompilerException: java.lang.NullPointerException: Cannot invoke "javax.lang.model.type.TypeMirror.getKind()" because "t" is null
        at org.codehaus.plexus..............
        ... 16 common frames omitted
Caused by: java.lang.RuntimeException: java.lang.NullPointerException: Cannot invoke "javax.lang.model.type.TypeMirror.getKind()" because "t" is null
        at jdk.compiler..................
        ... 18 common frames omitted
Caused by: java.lang.NullPointerException: Cannot invoke "javax.lang.model.type.TypeMirror.getKind()" because "t" is null
        at jdk.compiler/com.sun.tools.javac.model.JavacTypes.asElement(JavacTypes.java:75)
        at io.avaje.prism.internal.APContext.asTypeElement(APContext.java:235)
        at io.avaje.prism.internal.Util.isMeta(Util.java:15)
        at io.avaje.prism.internal.PrismGenerator.generatePrism(PrismGenerator.java:352)
        at io.avaje.prism.internal.PrismGenerator.generateIfNew(PrismGenerator.java:314)
        at io.avaje.prism.internal.PrismGenerator.process(PrismGenerator.java:258)
        at jdk.compiler/com.sun.tools.javac.processing.JavacProcessingEnvironment.callProcessor(JavacProcessingEnvironment.java:1021)
        at jdk.compiler/com.sun.tools.javac.processing.JavacProcessingEnvironment.discoverAndRunProcs(JavacProcessingEnvironment.java:937)
        at jdk.compiler/com.sun.tools.javac.processing.JavacProcessingEnvironment$Round.run(JavacProcessingEnvironment.java:1265)
        at jdk.compiler/com.sun.tools.javac.processing.JavacProcessingEnvironment.doProcessing(JavacProcessingEnvironment.java:1380)
        at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.processAnnotations(JavaCompiler.java:1271)
        at jdk.compiler/com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:948)
        at jdk.compiler/com.sun.tools.javac.api.JavacTaskImpl.lambda$doCall$0(JavacTaskImpl.java:104)
        at jdk.compiler/com.sun.tools.javac.api.JavacTaskImpl.invocationHelper(JavacTaskImpl.java:152)
        ... 21 common frames omitted

If not using -e, you simply get Cannot invoke "javax.lang.model.type.TypeMirror.getKind()" because "t" is null.
... which is true, since the class doesn't exist.