[SILGen] Fix case emission when there are no case body vars

We want to call the `bodyEmitter`, since that has the extra logic
necessary to handle `do-catch` statements. Previously this didn't
cause any issues since `hasCaseBodyVariables` would have always been
true for parsed `do-catch`s, but I'm planning on changing that.

Author: hamishknight

lib/SILGen/SILGenPattern.cpp

@@ -2958,7 +2958,7 @@ void PatternMatchEmission::emitSharedCaseBlocks(
     SWIFT_DEFER { assert(SGF.getCleanupsDepth() == PatternMatchStmtDepth); };
 
     if (!caseBlock->hasCaseBodyVariables()) {
-      emitCaseBody(caseBlock);
+      bodyEmitter(caseBlock);
       continue;
     }
 

test/SILGen/pr-84149.swift

@@ -0,0 +1,15 @@
+// RUN: %target-swift-emit-silgen %s -verify
+
+enum E : Error {
+  case a(Int), b(Int)
+}
+
+func bar() throws {}
+
+// Make sure we can correctly emit this without crashing.
+func foo() throws {
+  do {
+    try bar()
+  } catch E.a, E.b {
+  }
+}