Here the original manuscript does not have an and (which Oliver Cowdery would have written as an ampersand) after the yea. When Oliver copied this passage into the printer’s manuscript, he accidentally inserted an ampersand, which was then typeset in the 1830 edition as and.
The first part of this verse already mentions that the Lord had sent an angel to speak to Alma, so there is no need to have an and when the yea-clause begins. The connective yea is used in the Book of Mormon text to amplify what has just been said. The original reading suggests that Alma wants to emphasize that this angel spoke to him face to face. The intrusive and seems to imply that this information is almost an afterthought. The original reading without the and puts the proper emphasis on how the angel appeared before Alma.
There is nothing wrong, of course, with having the subject pronoun I immediately follow yea in the text; elsewhere in the original text there are 62 occurrences of yea I. As expected, yea and I also occurs in the text (24 times originally). In each case, we follow the earliest textual sources.
Summary: In accord with the reading of the original manuscript, remove the intrusive and after the yea in Alma 38:7, thus providing a more appropriate connection with the first part of the verse.