klocwork: fix risk issues

tools/hscollider/DatabaseProxy.h

@@ -61,7 +61,7 @@ public:
         std::lock_guard<std::mutex> lock(mutex);
         if (failed) {
             // We have previously failed to compile this database.
-            return nullptr;
+            throw CompileFailed("Unable to compile db previously.");
         }
         if (db) {
             return db;

tools/hscollider/NfaGeneratedCorpora.cpp

@@ -101,7 +101,7 @@ void NfaGeneratedCorpora::generate(unsigned id, vector<Corpus> &data) {
         pl.logicalKeyRenumber();
         const auto &m_lkey = pl.getLkeyMap();
         assert(!m_lkey.empty());
-        u32 a_subid; // arbitrary sub id
+        u32 a_subid = 0; // arbitrary sub id
         unordered_map<u32, vector<Corpus>> m_data;
         for (const auto &it : m_lkey) {
             a_subid = it.first;

tools/hscollider/Thread.cpp

@@ -98,6 +98,6 @@ void *Thread::runThread(void *thr) {
 }
 
 
-Thread::Thread(size_t num) : thread_id(num) {}
+Thread::Thread(size_t num) : thread_id(num), thread() {}
 
 Thread::~Thread() {}