Is gum, secreted by some trees, forbidden if used in chocolate ingredients?

The fundamental principle for tree resin is that it is permissible, due to the generality of the scriptural evidences that permit what is in the earth and make lawful good things, such as His — Exalted be He — saying: "It is He who created for you all of that which is on the earth" and His saying: "O mankind, eat from whatever is on earth [that is] lawful and good." What is excluded from this is that which is proven to be harmful, due to the Prophet's — peace and blessings be upon him — saying: "There should be neither harm nor reciprocal harm." This is also indicated by the Hadith: "The lawful is what Allah has made lawful in His Book, and the unlawful is what Allah has made unlawful in His Book, and what He has remained silent about is among that which He has pardoned." Thus, the default for things is permissibility unless there is a scriptural evidence for their prohibition.