We shouldn't throw under FLAG_debug_code, rather abort.

src/arm/full-codegen-arm.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 3440 matching lines @@
   Register index = r1;
   Register value = r2;
 
   VisitForStackValue(args->at(1));  // index
   VisitForStackValue(args->at(2));  // value
   VisitForAccumulatorValue(args->at(0));  // string
   __ Pop(index, value);
 
   if (FLAG_debug_code) {
     __ SmiTst(value);
-    __ ThrowIf(ne, kNonSmiValue);
+    __ Check(eq, kNonSmiValue);
     __ SmiTst(index);
-    __ ThrowIf(ne, kNonSmiIndex);
+    __ Check(eq, kNonSmiIndex);
     __ SmiUntag(index, index);
     static const uint32_t one_byte_seq_type = kSeqStringTag | kOneByteStringTag;
     __ EmitSeqStringSetCharCheck(string, index, value, one_byte_seq_type);
     __ SmiTag(index, index);
   }
 
   __ SmiUntag(value, value);
   __ add(ip,
          string,
          Operand(SeqOneByteString::kHeaderSize - kHeapObjectTag));
@@ skipping 10 matching lines @@
   Register index = r1;
   Register value = r2;
 
   VisitForStackValue(args->at(1));  // index
   VisitForStackValue(args->at(2));  // value
   VisitForAccumulatorValue(args->at(0));  // string
   __ Pop(index, value);
 
   if (FLAG_debug_code) {
     __ SmiTst(value);
-    __ ThrowIf(ne, kNonSmiValue);
+    __ Check(eq, kNonSmiValue);
     __ SmiTst(index);
-    __ ThrowIf(ne, kNonSmiIndex);
+    __ Check(eq, kNonSmiIndex);
     __ SmiUntag(index, index);
     static const uint32_t two_byte_seq_type = kSeqStringTag | kTwoByteStringTag;
     __ EmitSeqStringSetCharCheck(string, index, value, two_byte_seq_type);
     __ SmiTag(index, index);
   }
 
   __ SmiUntag(value, value);
   __ add(ip,
          string,
          Operand(SeqTwoByteString::kHeaderSize - kHeapObjectTag));
@@ skipping 1398 matching lines @@
   ASSERT(Memory::uint32_at(interrupt_address_pointer) ==
          reinterpret_cast<uint32_t>(
              isolate->builtins()->OsrAfterStackCheck()->entry()));
   return OSR_AFTER_STACK_CHECK;
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM