[dartfuzz] Remove duplicate map keys

In dartfuzz_api_table.dart, both `DartType.VOID` and `DartType.VOID_NULLABLE` are added to the Map keys. At runtime, the last value for a given key wins, so I removed the `DartType.VOID` key-value pair.

In gen_api_table.dart, both `assertionErrorEncoding` and `errorEncoding` are added to the Map keys. At runtime, the last value for a given key wins, so I removed the `assertionErrorEncoding` key-value pair.

This CL should be a no-op.

Bug: #50796
Change-Id: Ifcfeb3e84930267f60efd2eb009a722f8ac2453e
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/279234
Reviewed-by: Tess Strickland <[email protected]>
Commit-Queue: Samuel Rawlins <[email protected]>

Author: srawlins

runtime/tools/dartfuzz/dartfuzz_api_table.dart

@@ -86,7 +86,6 @@ class DartLib {
     DartType.UINT8CLAMPEDLIST_NULLABLE: uint8ClampedListLibsNullable,
     DartType.UINT8LIST: uint8ListLibs,
     DartType.UINT8LIST_NULLABLE: uint8ListLibsNullable,
-    DartType.VOID: voidLibs,
     DartType.VOID_NULLABLE: voidLibsNullable,
   };
   static const typedDataFloatTypes = [

runtime/tools/dartfuzz/gen_api_table.dart

@@ -167,7 +167,6 @@ final Map<String, String> typeToLibraryMethodsListName = () {
     abstractClassInstantiationErrorEncoding:
         abstractClassInstantiationErrorLibs,
     argumentErrorEncoding: argumentErrorLibs,
-    assertionErrorEncoding: assertionErrorLibs,
     boolEncoding: boolLibs,
     byteDataEncoding: byteDataLibs,
     castErrorEncoding: castErrorLibs,