the syntax error is not related and has already been fixed.
the intercom attempt is part of macro-exten-vm
You also have to make sure that your intercom feature code is enabled (*80 default) which it used to not be enabled at install time though new systems starting 2.9 it is enabled when first installed. (This needs to be enabled or the paging module will not generate the dialplan necessary for it to work, I guess we could detect that and inform of the issue…).
you need to have the paging module installed for it to try it, and of course you need it configured correctly, either forcing every extension or enabling the specific target extension.
The code generated is going to look different depending on various configuration choices but here is an example of what the code looks like where it would be attempting to to the intercom all if appropriate:
exten => s,n,Noop([TRACE](3) AMPUSER: ${AMPUSER}, FROM_DID: ${FROM_DID}, answermode: ${DB(AMPUSER/${EXTTOCALL}/answermode)}, BLINDTXF: ${BLINDTRANSFER}, EXT_STATE: ${EXTENSION_STATE(${EXTTOCALL})})
exten => s,n,GotoIf($["${AMPUSER}"=""|${LEN(${FROM_DID})}|"${DB(AMPUSER/${EXTTOCALL}/answermode)}"!="intercom"|${LEN(${BLINDTRANSFER})}|"${EXTENSION_STATE(${EXTTOCALL})}"!="NOT_INUSE"|"${CC_RECALL}"=""]?macrodial)
exten => s,n,Set(INTERCOM_EXT_DOPTIONS=${DIAL_OPTIONS})
exten => s,n,Set(INTERCOM_RETURN=TRUE)
exten => s,n,Gosub(ext-intercom,*80${EXTTOCALL},1)
exten => s,n,Set(INTERCOM_RETURN=)
exten => s,n,Set(INTERCOM_EXT_DOPTIONS=)
exten => s,n(macrodial),GosubIf($["${INTERCOM_CALL}"="TRUE" & ${LEN(${BLINDTRANSFER})}]?clrheader,1)
exten => s,n,Macro(dial-one,${RT},${DIAL_OPTIONS},${EXTTOCALL})