Core/Misc: Fix some static analysis issues

Add some asserts and additional NULL checks as sanity checks.

src/server/scripts/Spells/spell_priest.cpp

@@ -237,6 +237,7 @@ class spell_pri_glyph_of_prayer_of_healing : public SpellScriptLoader
                 PreventDefaultAction();
 
                 SpellInfo const* triggeredSpellInfo = sSpellMgr->GetSpellInfo(SPELL_PRIEST_GLYPH_OF_PRAYER_OF_HEALING_HEAL);
+                ASSERT(triggeredSpellInfo);
                 int32 heal = int32(CalculatePct(int32(eventInfo.GetHealInfo()->GetHeal()), aurEff->GetAmount()) / triggeredSpellInfo->GetMaxTicks());
                 GetTarget()->CastCustomSpell(SPELL_PRIEST_GLYPH_OF_PRAYER_OF_HEALING_HEAL, SPELLVALUE_BASE_POINT0, heal, eventInfo.GetProcTarget(), true, NULL, aurEff);
             }