Code style: fix simplified code and restore correct functionality.

Author: kfriedberger

src/org/sosy_lab/java_smt/solvers/cvc5/CVC5FormulaCreator.java

@@ -108,7 +108,7 @@ public Term makeVariable(Sort sort, String name) {
         "Symbol %s requested with type %s, but already used with type %s",
         name,
         sort,
-        Iterables.getOnlyElement(variablesCache.row(name).entrySet()));
+        Iterables.getOnlyElement(variablesCache.row(name).entrySet()).getKey());
     Term newVar = termManager.mkConst(sort, name);
     variablesCache.put(name, sort.toString(), newVar);
     return newVar;
@@ -851,7 +851,7 @@ private Term accessVariablesCache(String name, Sort sort) {
         "Symbol %s requested with type %s, but already used with type %s",
         name,
         sort,
-        Iterables.getOnlyElement(variablesCache.row(name).entrySet()));
+        Iterables.getOnlyElement(variablesCache.row(name).entrySet()).getKey());
     return existingVar;
   }
 }