Allow adding extra flags to LaTeX compiler through environment variable

services/web/app/src/Features/Compile/ClsiManager.mjs

@@ -1114,7 +1114,7 @@ async function _getContentFromMongo(projectId) {
 
 function _finaliseRequest(projectId, options, project, docs, files) {
   const resources = []
-  let flags
+  let flags = []
   let rootResourcePath = options.rootResourcePath
   let rootResourcePathOverride = null
   let hasMainFile = false
@@ -1182,9 +1182,13 @@ function _finaliseRequest(projectId, options, project, docs, files) {
   if (options.fileLineErrors) {
     flags = ['-file-line-error']
   }
+  if (process.env.TEX_COMPILER_EXTRA_FLAGS) {
+    flags.push(...process.env.TEX_COMPILER_EXTRA_FLAGS.split(/\s+/).filter(Boolean))
+  }
   const hasPremiumCompiles = ['alpha', 'priority'].includes(
     options.compileGroup
   )
+
   return {
     compile: {
       options: {