Remove unreachable code and fix typos in converter.cpp (#181)

Three minor correctness/quality fixes in
`cpp2rust/converter/converter.cpp`.

## Changes

- **Remove dead `std::unreachable()`** — the call after a `switch` block
where every case (including `default`) already ends with `return
true`/`return false` can never be reached.
- **Fix typo in assert message** — `"less that total size"` → `"less
than total size"`
- **Fix typo in comment** — `"Take supress before"` → `"Take suppress
before"`

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>

Author: Copilot

cpp2rust/converter/converter.cpp

@@ -2354,7 +2354,6 @@ bool Converter::ConvertIncAndDec(clang::UnaryOperator *expr) {
   default:
     return false;
   }
-  std::unreachable();
 }
 
 bool Converter::VisitUnaryOperator(clang::UnaryOperator *expr) {
@@ -2814,7 +2813,7 @@ bool Converter::VisitInitListExpr(clang::InitListExpr *expr) {
       if (auto arr_ty = ctx_.getAsConstantArrayType(expr->getType())) {
         assert(
             (arr_ty->getSize().getZExtValue() - expr->getNumInits()) &&
-            "Number of initializers should be less that total size of array");
+            "Number of initializers should be less than total size of array");
         for (unsigned i = 0;
              i < arr_ty->getSize().getZExtValue() - expr->getNumInits(); ++i) {
           ConvertVarInit(expr->getArrayFiller()->getType(),
@@ -3002,7 +3001,7 @@ bool Converter::VisitCXXConstructExpr(clang::CXXConstructExpr *expr) {
   if (ctor->isCopyOrMoveConstructor() ||
       (ctor->isConvertingConstructor(false) && ctor->getNumParams() == 1 &&
        ctor->getParamDecl(0)->getType()->isRValueReferenceType())) {
-    // Take supress before recursing into the child.
+    // Take suppress before recursing into the child.
     bool suppress = PushSuppressIteratorClone::take(*this);
     Convert(expr->getArg(0));
     if (ctor->isCopyConstructor() && !suppress) {