Verb + de + infinitive
craindre
deno preposition
The constructions
decraindre de + infinitif
Meaning : to be afraid of doing
Je crains de me tromper.
no prepositioncraindre quelque chose
Meaning : to fear something
Il craint la chaleur.
Why
Craindre de before an infinitive, plain craindre before a noun: craindre le froid, craindre son patron. Avoir peur de, more common, takes de in both cases.