Updated README file to fix readability and add some common debug info

L1Trigger/L1TZDC/README.md

@@ -1,4 +1,35 @@
-Basic build instructions, integratable into Molly's L1Emulator instructions with the Run 3 HI menu using CMSSW_13_1_0_pre4
+***** COMMON FIXES ON FAIL (Skip to below for build instructions *****
+
+If you see output like the following
+```
+----- Begin Fatal Exception 18-Aug-2023 22:34:50 CEST-----------------------
+An exception of category 'ProductNotFound' occurred while
+   [0] Processing  Event run: 326295 lumi: 4 event: 32601 stream: 0
+   [1] Running path 'zdcEtSum'
+   [2] Calling method for module L1TZDCProducer/'zdcEtSumProducer'
+Exception Message:
+Principal::getByToken: Found zero products matching all criteria
+Looking for type: HcalDataFrameContainer<QIE10DataFrame>
+Looking for module label: hcalDigis
+Looking for productInstanceName: ZDC
+Looking for process: reRECO
+   Additional Info:
+      [a] If you wish to continue processing events after a ProductNotFound exception,
+add "SkipEvent = cms.untracked.vstring('ProductNotFound')" to the "options" PSet in the configuration.
+
+----- End Fatal Exception -------------------------------------------------
+```
+
+The issue is almost certainly the inclusion of "reRECO" as a third argument \
+for the zdcToken input tag to zDCEtSumProducer \
+(CM note: putting this at the tope as I have forgotten \
+this issue twice now)
+
+**********************************************************************
+
+
+Basic build instructions, integratable into Molly's L1Emulator instructions \
+with the Run 3 HI menu using CMSSW_13_1_0_pre4 \
 Found here: https://github.com/mitaylor/L1StudiesFramework/tree/main/RunPbPbL1Ntuples
 
 To build, do
@@ -45,16 +76,21 @@ cd ../../../../../
 scram b -j 8
 ```
 On a good build we need to edit customiseUtils.py per Molly's instructions:
+
 emacs -nw L1Trigger/Configuration/python/customiseUtils.py
+
 process.TriggerMenu.L1TriggerMenuFile = cms.string('L1Menu_Collisions2022_v1_2_0.xml') → process.TriggerMenu.L1TriggerMenuFile = cms.string('L1Menu_CollisionsHeavyIons2023_v0_0_1.xml')
 
 Create the python by grabbing Molly's runCmsDriver for 2018 data
+```
 wget https://raw.githubusercontent.com/mitaylor/L1StudiesFramework/main/RunPbPbL1Ntuples/runCmsDriver_2018Data.sh
 cmsRun runCmsDriver_2018Data.sh
+```
 
 We need to modify the output, l1Ntuple_2018Data.py
 Towards the end add this block
 ****************************
+```
 process.l1UpgradeTree.sumZDCPToken = cms.untracked.InputTag("zdcEtSumProducer", "zdcEtSumsP")
 process.l1UpgradeTree.sumZDCMToken = cms.untracked.InputTag("zdcEtSumProducer", "zdcEtSumsM")
 
@@ -67,7 +103,8 @@ process.zdcEtSumProducer = cms.EDProducer('L1TZDCProducer',
 
 process.zdcEtSum = cms.Path(process.zdcEtSumProducer)
 process.schedule.append(process.zdcEtSum)
-
+```
 ****************************
 
+
 This should run out of the box - if it does not please contact me (cfmcginn) or ginnocen @ github