Bug in phi-calculus parser

See #2930, release log:

• a7e3a63 by @maxonfjvipon: fix(#2930): checkstyle
• 4591a44 by @maxonfjvipon: fix(#2930): vertex
• 633908b by @maxonfjvipon: Merge branch 'master' into fix...
• e64f050 by @maxonfjvipon: fix(#2930): simplified phi gra...
• d1249b2 by @renovate[bot]: chore(deps): update actions/ch...
• 74d04a4 by @rultor: Merge branch '__rultor'
• 6b317f8 by @c71n93: #2863 slightly change the mess...
• 80f0434 by @c71n93: #2863 fix documentation again
• 0d5bbfb by @c71n93: #2863 fix documentation
• 1bce14b by @renovate[bot]: chore(deps): update teatimegue...
• 3be2745 by @c71n93: #2863 use dirty hacks to reduc...
• deab685 by @rultor: Merge branch '__rultor'

Released by Rultor 2.0-SNAPSHOT, see build log