Replace a string if it is not followed by another string - json

Question

I would like to replace the fortawesome string (if it is not followed by the /fontawesome-common-type string) by the stephane string.
sed -e 's,"#fortawesome(/^fontawesome-common-types+),"#stephaneeybert\1,g'
sed: -e expression #1, char 65: invalid reference \1 on `s' command's RHS
An example input:
"#fortawesome/fontawesome-common-types": "^0.2.32"
"name": "#fortawesome/pro-duotone-svg-icons",
And its expected output:
"#fortawesome/fontawesome-common-types": "^0.2.32"
"name": "#stephane/pro-duotone-svg-icons",
UPDATE: I went with the simple alternative of using an intermediate variable:
EXCLUDE=fontawesome-common-types
BUFFER=EkSkLUdE
cat package/package.json \
| sed -e "s,\"#$REPO_SOURCE/$EXCLUDE,\"#$BUFFER,g" \
| sed -e "s,\"#$REPO_SOURCE,\"#$REPO_DEST,g" \
| sed -e "s,\"#$BUFFER,\"#$REPO_SOURCE/$EXCLUDE,g" \
> package/package.out.json;

Answer 1

sed doesn't support negative lookahead functionality. Other than the obvious perl fallback that supports lookaheads, uou may use this awk as a work-around:
awk -F 'fortawesome' -v OFS='stephane' 'NF > 1 {
s = ""
for (i=1; i<NF; ++i)
s = s $i ($(i+1) ~ /^\/fontawesome-common-type/ ? FS : OFS)
$0 = s $i
} 1' file
This awk uses fortawesome as input field separator and stephane as OFS
NF > 1 will be true when we have fortawesome in a line
we loop through fields split by fortawesome and keep track of next field
if next field starts with /fontawesome-common-type then we keep same FS otherwise use OFS

Answer 2

Use temporary values:
exclude='fortawesome/fontawesome-common-type';
match='fortawesome';
repl='stephane';
tmpvar='EkSkLUdE';
sed "s#$exclude#$tmpvar#g;s#$match#$repl#g;s#$tmpvar#$exclude#g" file > newfile
All cases of exclude are replaced with tmpvars, then real expected matches are replaced with repls, and then tmpvars are changed back to excludes.