C. F. Keil and Franz Delitzsch on Lamentations 3:2

Lam 3:2 "Me hath He (God) led and brought through darkness (חשׁך, local accus.), and not light," is a combination like that in Job 12:25 and Amo 5:18. The path of Jeremiah’s life certainly lay through darkness, but was not wholly devoid of light, because God had promised him His protection for the discharge of his official functions. The complaint applies to all the godly, to whom, at the fall of Jerusalem, no light appeared to cheer the darkness of life’s pathway.