Improve error message for Robolectric.buildActivity() if provided an abstract class

[david-allison]

Is your feature request related to a problem? Please describe.
A developer wanted help with their code producing the following error message

Kotlin

        val controller = Robolectric.buildActivity(AbstractClass::class.java)

Stack Trace

    java.lang.RuntimeException: error instantiating com.ichi2.anki.AbstractFlashcardViewer
        at org.robolectric.util.ReflectionHelpers.callConstructor(ReflectionHelpers.java:440)
        at org.robolectric.Robolectric.buildActivity(Robolectric.java:113)
        at org.robolectric.Robolectric.buildActivity(Robolectric.java:78)
        at com.ichi2.anki.AbstractFlashcardViewerCommandTest.testRefreshIfRequired(AbstractFlashcardViewerCommandTest.kt:163)
        Caused by:
        java.lang.InstantiationException
            at java.base/jdk.internal.reflect.InstantiationExceptionConstructorAccessorImpl.newInstance(InstantiationExceptionConstructorAccessorImpl.java:48)
            at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:499)
            at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:480)
            at org.robolectric.util.ReflectionHelpers.callConstructor(ReflectionHelpers.java:438)
            ... 3 more

Describe the solution you'd like
The error message should state that the provided class is abstract (and that abstract classes are not supported)

Describe alternatives you've considered
N/A

Additional context

Sample isAbstract checking code

java.lang.reflect.Modifier.isAbstract(clazz.getModifiers())

https://stackoverflow.com/a/1072895

robolectric/shadowapi/src/main/java/org/robolectric/util/ReflectionHelpers.java

Lines 446 to 469 in 76048c0

	public static <R> R callConstructor(
	Class<? extends R> clazz, ClassParameter<?>... classParameters) {
	perfStatsCollector.incrementCount("ReflectionHelpers.callConstructor-" + clazz.getName());
	try {
	final Class<?>[] classes = ClassParameter.getClasses(classParameters);
	final Object[] values = ClassParameter.getValues(classParameters);
	Constructor<? extends R> constructor = clazz.getDeclaredConstructor(classes);
	constructor.setAccessible(true);
	return constructor.newInstance(values);
	} catch (InstantiationException e) {
	throw new RuntimeException("error instantiating " + clazz.getName(), e);
	} catch (InvocationTargetException e) {
	if (e.getTargetException() instanceof RuntimeException) {
	throw (RuntimeException) e.getTargetException();
	}
	if (e.getTargetException() instanceof Error) {
	throw (Error) e.getTargetException();
	}
	throw new RuntimeException(e.getTargetException());
	} catch (Exception e) {
	throw new RuntimeException(e);
	}
	}