Make InvalidIdentifier exception subclass of ExpressionError

Fixes test which instead of reporting error shows this exception:

[info] - expr_bad_id_inst_value *** FAILED ***
[info]   io.kaitai.struct.format.InvalidIdentifier: invalid ID: 'BAD', expected /^[a-z][a-z0-9_]*$/
[info]   at io.kaitai.struct.format.Identifier$.checkIdentifier(Identifier.scala:52)
[info]   at io.kaitai.struct.format.InstanceIdentifier.<init>(Identifier.scala:113)
[info]   at io.kaitai.struct.ClassTypeProvider.resolveMember(ClassTypeProvider.scala:83)
[info]   at io.kaitai.struct.ClassTypeProvider.determineType(ClassTypeProvider.scala:46)
[info]   at io.kaitai.struct.ClassTypeProvider.determineType(ClassTypeProvider.scala:20)
[info]   at io.kaitai.struct.translators.TypeDetector.detectTypeRaw(TypeDetector.scala:61)
[info]   at io.kaitai.struct.translators.TypeDetector.detectType(TypeDetector.scala:25)
[info]   at io.kaitai.struct.precompile.DeriveValueInstanceTypes.$anonfun$deriveValueType$2(DeriveValueInstanceTypes.scala:53)
[info]   at io.kaitai.struct.precompile.DeriveValueInstanceTypes.$anonfun$deriveValueType$2$adapted(DeriveValueInstanceTypes.scala:46)
[info]   at scala.collection.immutable.RedBlackTree$.foreach(RedBlackTree.scala:291)
[info]   ...

shared/src/main/scala/io/kaitai/struct/ClassTypeProvider.scala

@@ -68,7 +68,7 @@ class ClassTypeProvider(classSpecs: ClassSpecs, var topClass: ClassSpec) extends
     * @param inClass type specification to search member in
     * @param attrName name of a member to search for
     * @return member spec if found, or throws an exception
-    * @throws format.InvalidIdentifier if attribute name is not a valid name for a member
+    * @throws precompile.InvalidIdentifier if attribute name is not a valid name for a member
     * @throws precompile.FieldNotFoundError if attribute with such name is not found
     */
   def resolveMember(inClass: ClassSpec, attrName: String): MemberSpec = {

shared/src/main/scala/io/kaitai/struct/format/AttrSpec.scala

@@ -6,6 +6,7 @@ import io.kaitai.struct.datatype.DataType
 import io.kaitai.struct.datatype.DataType._
 import io.kaitai.struct.exprlang.Ast.expr
 import io.kaitai.struct.exprlang.{Ast, Expressions}
+import io.kaitai.struct.precompile.InvalidIdentifier
 import io.kaitai.struct.problems.KSYParseError
 
 import scala.collection.immutable.SortedMap

shared/src/main/scala/io/kaitai/struct/format/Identifier.scala

@@ -1,6 +1,7 @@
 package io.kaitai.struct.format
 
 import io.kaitai.struct.exprlang.Ast
+import io.kaitai.struct.precompile.InvalidIdentifier
 import io.kaitai.struct.problems.KSYParseError
 
 /**
@@ -37,10 +38,6 @@ case class NamedIdentifier(name: String) extends Identifier {
   override def humanReadable: String = name
 }
 
-case class InvalidIdentifier(id: String) extends RuntimeException(
-  s"invalid ID: '$id', expected /${Identifier.ReIdentifier.toString}/"
-)
-
 object Identifier {
   val ReIdentifier = "^[a-z][a-z0-9_]*$".r
 

shared/src/main/scala/io/kaitai/struct/format/ParseUtils.scala

@@ -2,6 +2,7 @@ package io.kaitai.struct.format
 
 import io.kaitai.struct.Utils
 import io.kaitai.struct.exprlang.{Ast, Expressions}
+import io.kaitai.struct.precompile.InvalidIdentifier
 import io.kaitai.struct.problems.KSYParseError
 
 object ParseUtils {

shared/src/main/scala/io/kaitai/struct/precompile/Exceptions.scala

@@ -1,14 +1,18 @@
 package io.kaitai.struct.precompile
 
 import io.kaitai.struct.datatype.DataType
-import io.kaitai.struct.format.ClassSpec
+import io.kaitai.struct.format.{ClassSpec, Identifier}
 import io.kaitai.struct.translators.MethodArgType
 
 /**
  * Base class for all expression-related errors, not localized to a certain path
  * in source file.
  */
 sealed abstract class ExpressionError(msg: String) extends RuntimeException(msg)
+
+class InvalidIdentifier(id: String)
+  extends ExpressionError(s"invalid ID: '$id', expected /${Identifier.ReIdentifier.toString}/")
+
 class TypeMismatchError(msg: String) extends ExpressionError(msg)
 class TypeUndecidedError(msg: String) extends ExpressionError(msg)
 class WrongMethodCall(val dataType: MethodArgType, val methodName: String, val expectedSigs: Iterable[String], val actualSig: String)

shared/src/main/scala/io/kaitai/struct/precompile/TypeValidator.scala

@@ -239,8 +239,6 @@ class TypeValidator(specs: ClassSpecs) extends PrecompileStep {
       detector.validate(expr)
       None
     } catch {
-      case err: InvalidIdentifier =>
-        Some(ErrorInInput(err, path ++ List(pathKey)))
       case err: ExpressionError =>
         Some(ErrorInInput(err, path ++ List(pathKey)))
     }
@@ -285,8 +283,6 @@ class TypeValidator(specs: ClassSpecs) extends PrecompileStep {
       detector.validate(expr)
       None
     } catch {
-      case err: InvalidIdentifier =>
-        Some(ErrorInInput(err, path ++ List(pathKey)))
       case err: ExpressionError =>
         Some(ErrorInInput(err, path ++ List(pathKey)))
     }