Improve JS Exception handling.

- Check for pending exceptions after function calls and script
executions.
- Call LOGERROR instead of JS_ReportError when there is a conversion
error in FromJSVal, since that can only be called from C++ (where JS
errors don't really make sense). Instead, C++ callers of FromJSVal
should handle the failure and, themselves, either report an error or
simply do something else.
- Wrap JS_ReportError since that makes updating it later easier.

This isn't a systematical fix since ToJSVal also ought return a boolean
for failures, and we probably should trigger errors instead of warnings
on 'implicit' conversions, rather a preparation diff.

Part of the SM52 migration, stage: SM45 compatible (actually SM52
incompatible, too).

Based on a patch by: Itms
Comments by: Vladislavbelov, Stan`
Refs #742, #4893

Differential Revision: https://code.wildfiregames.com/D3093
This was SVN commit r24187.

source/ps/scripting/JSInterface_ModIo.cpp

@@ -86,7 +86,7 @@ JS::Value JSI_ModIo::GetMods(ScriptInterface::CmptPrivate* pCmptPrivate)
 	}
 
 	ScriptInterface* scriptInterface = pCmptPrivate->pScriptInterface;
-	ScriptInterface::Request rq(scriptInterface);
+	ScriptRequest rq(scriptInterface);
 
 	const std::vector<ModIoModData>& availableMods = g_ModIo->GetMods();
 
@@ -132,7 +132,7 @@ JS::Value JSI_ModIo::GetDownloadProgress(ScriptInterface::CmptPrivate* pCmptPriv
 	}
 
 	ScriptInterface* scriptInterface = pCmptPrivate->pScriptInterface;
-	ScriptInterface::Request rq(scriptInterface);
+	ScriptRequest rq(scriptInterface);
 
 	const DownloadProgressData& progress = g_ModIo->GetDownloadProgress();